This invention relates to a ball joint which comprises a ball on the end of a ball pin for use in applications where the primary load on the ball joint is down the axis of the ball pin, the ball being received in a socket so that the ball pin can move angularly relative to the socket, without play. The ball joint thus allows two components to be connected so that they can remain connected and motion can be transmitted between them, over a range of relative angular positions.
1. Field of the Invention
Ball joints of the kind described are used in particular in vehicle suspension and steering mechanisms, and the present invention is particularly suitable for use in a vehicle suspension system. However, the invention is not limited to this application.
2. Disclosure Information
A problem with such ball joints is that the socket is liable to become worn over time, eventually allowing the ball pin to leave the socket with potentially dangerous consequences. One arrangement for reducing this problem has been proposed in U.S. Pat. No. 4,679,957. In this arrangement, a secondary ball is provided, which bears against a secondary bearing surface in the event that the primary ball is freed from its socket. The secondary ball is connected to the primary ball by a shaft, and the secondary ball and the shaft are housed in a slot which permits translation in one dimension. The secondary ball is in contact with a microswitch that triggers an alarm when contact is lost. This arrangement provides a warning that dangerous wear has occurred, and a failsafe mechanism for limiting danger from loss of the pin from the socket. However, it is complex in construction, does not permit full movement of the ball pin, and wear is likely over the relatively small area of contact between the secondary ball and the microswitch.